Double die-cutting



April 14, 1964 F. E. MILLER 3,123,681

DOUBLE DIE-CUTTING Filed Oct. 25, 1961 5 Sheets-Sheet 1 INVENTOR FREDERICK E. MILLER ATTORNEYS A ril 14, 1964 F. E. MILLER 3,123,531

- DOUBLE DIE-CUTTING Filed Odt. 25, 1961 :s Sheets-Sheet 2 FIG. 4

INVENTOR FREDERICK E. MILLER April 14, 1964 Filed Oct. 25, 1961 F. E. MILLER DOUBLE DIE-CUTTING 5 Sheets-Sheet 3 BYZ INVENTOR FREDERICK E MILLER ATTORN EYS a lie.

United States Patent Ofi ice 3,128,681 Patented Apr. 14, 1964 3,128,681 DOUBLE DIE-CUTTING Frederick E. Miller, London, Ontario, Canada, assignor to Somerville Industries Limited, London, Ontario, Canada Filed Oct. 25, 1961, Ser. No. 147,687 2 Claims. (Cl. 93-58) This invention relates to the fabrication of paperboard and cardboard cartons and the like, and particularly relates to a method and apparatus for die cutting a carton blank so as to form a zone of weakness in the blank which is capable of defining one edge of a tear strip or the like in the set-up carton.

There are two standard closure methods for paperboard cartons. The first method involves some sort of closure flap which may tuck into or interlock with the main body of the carton. The second method involves a seal as well as a closure and is often effected by gluing the closure flaps in place. When the latter type of carton is opened it must be torn or cut, and it is common to provide a tear-strip or punch-out which will readily separate from the carton under the influence of properly applied pressure.

The present invention is mainly concerned with that type of carton having the tear strip or punch-out method of opening, although the invention does have use in other types of cartons as well. Heretofore, the usual method of providing a tear strip has been to define the tear strip by lines of perforations or semi-perforations whereby the material of the carton blank along these lines is weakened. A fairly recent innovation suggests the formation of a line of weakness in a carton blank by cutting partially through the blank from both sides of the blank along parallel adjacent lines. The zone of weakness thus created is remarkably efficient as one edge of a tear strip or the like. However, this latter method of forming a tear strip has not proved economically feasible since it has heretofore been necessary to perform two separate die cutting operations on each blank, in order to make cuts from opposite sides of the blank. Accordingly, an extra manufacturing step has been necessary in order to provide a carton blank having a tear strip of the type just described.

It is an object of this invention to provide a method and apparatus for die-cutting a carton blank so as to form a tear strip or the like in the carton blank, wherein the side edges of the tear strip are defined by partial cuts through the blank from opposite sides thereof.

It is a further object of this invention to provide a method and apparatus for achieving the above described tear strip in a carton blank with one pass through a diecutting apparatus so as to eliminate the extra manufacturing step hitherto required.

With these and other objects in mind, the apparatus in accord with this invention essentially consists of a cutting die and means for pressing a carton blank against the cutting die such as a platen of a platen press or a cylinder jacket of a cylinder press and a pair of cutting knives, one of which is carried by the cutting die in the usual manner, the other being carried by the platen or cylinder jacket. To back the carton blank opposite the cutting knife carried by the platen or cylinder jacket, the cutting die is also provided with an anvil. With this apparatus, it is possible to achieve partial cuts through the carton blank from both sides thereof with one passage of the carton blank through the press.

The invention will be more fully understood from the following description of several embodiments thereof as read in conjunction with the accompanying drawings.

In the drawings:

FIGURE 1 is a perspective view partly broken away, of

the essential components of a cylinder press in accord with the present invention,

FIGURE 2 is an enlarged perspective view of a cutting knife for attachment to the cylinder jacket of the cylinder press in accord with this invention,

FIGURE 3 is a vertical cross-sectional View taken along line 33 of FIGURE 1,

FIGURE 4 is a view similar to FIGURE 3 but shows, in addition, a sheet of paperboard being pressed against the cutting die by the cylinder jacket.

FIGURE 5 is an enlarged detailed view of a portion of FIGURE 4,

FIGURE 6 is a view similar to FIGURE 5 but emphasizing a particular method of aflixing a cutting knife to the jacket of the cylinder press, and

FIGURES 7, 8 and 9 illustrate additional forms of cutting knives.

Referring to FIGURE 1, it will be appreciated that the apparatus illustrated therein is basically the well-known cylinder press equipment for die-cutting carton blanks and the like. The equipment essentially consists of a cutting die 10 and a cylinder 11 around which is wrapped a sheet of paperboard 12 which is to be die-cut. As is the usual practice, cutting die 10 is made up of several individual dies 10a, each one defining a carton blank.

With the cylinder press apparatus illustrated, the paperboard sheet 12 is die-cut by passing the cutting die 10 beneath the cylinder 11 while exerting pressure therebetween. Each carton blank is left connected to the surrounding blanks so that sheet 12 will remain in sheet form until all of the blanks have been demarked therefrom. Prior to the present invention, and when it was desired to out only partially through the blank from both sides so as to form one edge of a tear strip or the like, it has been necessary to remove the paperboard sheet from the first cylinder after the first pass has been made, and then wrap the sheet around a second cylinder and make a second pass over a second die. In accord with the present invention, however, the partial cuts from opposite sides can be made with only one pass through the die cutting apparatus.

Referring still to FIGURE 1, the object of the present invention is achieved by affixing cutting knives 14 to the jacket of cylinder 11 beneath the paperboard sheet 12.

As can best be seen in FIGURE 2, the particular cutting knives 14 illustrated are formed of strips of steel or the like having two cutting edges 14a and 14b. These particular knives make two parallel cuts on the inside. surface of paperboard sheet 12, as the cylinder 11 is pressed against die 10. The cutting edges 14a and 14b are so dimensioned as to only partially cut through the paperboard sheet 12 so that similar cuts made On the opposite side of the paperboard sheet 12 will combine with the first cuts on the inside surface to form a line or zone of Weakness in the paperboard.

To provide surfaces against which the cutting edges 14a and 14b may work, each of the dies 10a contained in cutting die 10 are provided with strip-like anvils 15. It will be appreciated that these anvils are necessary to achieve a clean cut with the knives 14, otherwise the paperboard sheet will be simply bowed outwardly by the knives 14.

FIGURES 3, 4 and 5 illustrate the actual pressing step between the cylinder jacket 11a and the die 10. The cutting edges 14a and 14b carried by the jacket 11a work against anvils 15 while at the same time cutting knives 16, in the die, partially cut through the carton blank 12 from the opposite side.

FIGURES 7, 8 and 9 show alternate forms of cutting knives which may be afiixed to the jacket of the cutting cylinder and in the case of the platen press may be afiixed to the surface of the upper platen. It will be appreciated that these cutting knives may take almost any form, depending on the particular cut it is desired to make. Knives 14 are attached to the cylinder jacket or upper platen surface by an adhesive or by paper make ready. The latter method is illustrated by FIGURE 6.

This invention has been illustrated with particular reference to the formation of tear strips. However, it will be understood that the invention has broad utility in the paperboard and cardboard die cutting industry. For example, in the manufacture of cartons for containing fine grained granular materials it has previously been proposed to partially cut through the corner forming areas of the blanks whereby to form corner sealing ears in the locked cartons. Such a proposal has not been followed up because the formation of the sealing ears has required a second die-cutting operation whereby to partially cut through the carton blanks from the side opposite the side on which the main die-cutting operation is made. In accord with the present invention, however, such a proposal is now practical since the ear forming cuts can be made as the main die-cutting operation takes place.

What I claim as my invention is:

1. An apparatus for die-cutting a carton blank as to form a zone of weakness in the blank, said apparatus comprising cutting die means, cylinder jacket means for pressing said blank against said die means, a first cutting knife carried by said die means, said first knife being of a height to only partially cut through said blank when said blank is pressed against said die means, a second cutting knife carried on the outer surface of said cylinder jacket pressing means beneath said blank, said second knife consisting of an upstanding sharpened ridge in a flat strip of flexible tool steel and also being of a height to only partially cut through said blank when said blank is pressed against said die means, and anvil means carried by said die means to back said blank on said second cutting knife, said first and second knives being generally parallel to each other but spaced in the direction taken transverse to their longitudinal axes whereby to form a linear zone of weakness capable of forming one edge of a tear strip in a carton blank.

2. An apparatus for die-cutting a carton blank as to form a zone of weakness in the blank, said apparatus comprising cutting die means, cylinder jacket means for pressing said blank against said die means, a first cutting knife carried by said die means, said first knife being of a height to only partially cut through said blank when said blank is pressed against said die means, a second cutting knife carried on the outer surface of said cylinder jacket pressing means beneath said blank, said second knife consisting of an upstanding sharpened ridge formed along one side edge of a flat strip of flexible tool steel and also being of a height to only partially cut through said blank when said blank is pressed against said die means, and anvil means carried by said die means to back said blank on said second cutting knife, said first and second knives being generally parallel to each other but spaced in the direction taken transverse to their longitudinal axes whereby to form a linear zone of weakness capable of forming one edge of a tear strip in a carton blank.

References Cited in the file of this patent UNITED STATES PATENTS 2,5l5,863 Davidson July 18, 1950 2,524,962 Dalsemer Oct. 10, 1950 2,949,827 Kempen et al Aug. 23, 1960 3,020,809 Guyer et al. Feb. 13, 1962 

1. AN APPARATUS FOR DIE-CUTTING A CARTON BLANK AS TO FORM A ZONE OF WEAKNESS IN THE BLANK, SAID APPARATUS COMPRISING CUTTING DIE MEANS, CYLINDER JACKET MEANS FOR PRESSING SAID BLANK AGAINST SAID DIE MEANS, A FIRST CUTTING KNIFE CARRIED BY SAID DIE MEANS, SAID FIRST KNIFE BEING OF A HEIGHT TO ONLY PARTIALLY CUT THROUGH SAID BLANK WHEN SAID BLANK IS PRESSED AGAINST SAID DIE MEANS, A SECOND CUTTING KNIFE CARRIED ON THE OUTER SURFACE OF SAID CYLINDER JACKET PRESSING MEANS BENEATH SAID BLANK, SAID SECOND KNIFE CONSISTING OF AN UPSTANDING SHARPENED RIDGE IN A FLAT STRIP OF FLEXIBLE TOOL STEEL AND ALSO BEING OF A HEIGHT TO ONLY PARTIALLY CUT THROUGH SAID BLANK WHEN SAID BLANK IS PRESSED AGAINST SAID DIE MEANS, AND ANVIL MEANS CARRIED BY SAID DIE MEANS TO BACK SAID BLANK ON SAID SECOND CUTTING KNIFE, SAID FIRST AND SECOND KNIVES BEING GENERALLY PARALLEL TO EACH OTHER BUT SPACED IN THE DIRECTION TAKEN TRANSVERSE TO THEIR LONGITUDINAL AXES WHEREBY TO FORM A LINEAR ZONE OF WEAKNESS CAPABLE OF FORMING ONE EDGE OF A TEAR STRIP IN A CARTON BLANK. 